Method of modifying cell and global connection routing method

ABSTRACT

A method of modifying a cell includes identifying a maximum overlapped pin group. The method further includes determining a number of pins in the maximum overlapped pin group. The method further includes determining a span region of the maximum overlapped pin group. The method further includes comparing the number of pins and the span region to determine a global tolerance of the cell. The method further includes increasing a length of at least one pin of the maximum overlapped pin group in response to the global tolerance failing to satisfy a predetermined threshold. The method further includes fabricating a mask based on the increased length of the at least one pin.

PRIORITY CLAIM

The present application is a continuation of U.S. application Ser. No.14/813,483, filed Jul. 30, 2015, which is incorporated herein byreference in its entirety.

BACKGROUND

A circuit layout includes one or more standard cells which correspond toactive devices having a specific functionality. Cells for active deviceswhich are routinely repeated are often included in a cell library. Thesecells are called standard cells in some instances. Cells include pins,which are used to convey signals into and out of the cell. At least onepin of a cell is connected to a pin of at least one other cell in orderto transfer signals between the various cells. Routing lines areprovided to interconnect the pins of various cells to facilitate signaltransfer between different cells to provide a desired functionality forthe circuit layout.

As technology nodes decrease, flexibility for routing lines is decreaseddue to smaller distances between cells and between elements withincells. For example, at technology nodes of 10 nanometers or less, atleast one metal level includes routing lines extending only in a singledirection. This routing scheme is called one-dimensional routing in someembodiments. A metal level is a layer of conductive lines in a planehaving a nearly uniform distance from a substrate. Global connectionsare routing lines which extend across one or more standard cells. Insome instances, global connections extend across an entirety of thecircuit layout. Global connections only extend in one direction forcircuit layouts which include one-dimensional routing.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A-1 is a plan view of a circuit layout including a cell inaccordance with some embodiments.

FIG. 1A-2 is a plan view of a circuit layout including a modified cellin accordance with some embodiments.

FIG. 1B is an enlarged plan view of a cell in accordance with someembodiments.

FIG. 2 is a plan view of a cell in a circuit layout in accordance withsome embodiments.

FIG. 3 is a plan view of a cell in a circuit layout in accordance withsome embodiments.

FIG. 4A is a plan view of a circuit layout including a cell and ablocking shape in accordance with some embodiments.

FIG. 4B is a plan view of a circuit layout including two cells and ablocking shape in accordance with some embodiments.

FIG. 4C is a plan view of a circuit layout including two cells and ablocking shape in accordance with some embodiments.

FIG. 5A is a flow chart of a method of modifying a cell based on globalconnection routing in accordance with some embodiments.

FIG. 5B is a flow chart of a method of designing a circuit layout basedon global connection routing in accordance with some embodiments.

FIG. 6 is a plan view of a cell including pins in accordance with someembodiments.

FIG. 7 is a plan view of a cell including pins and blocking shapes inaccordance with some embodiments.

FIG. 8 is a schematic diagram of a specific purpose system forimplementing a method of global connection routing in accordance withsome embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

FIG. 1A-1 is a plan view of a circuit layout 100 including a cell inaccordance with some embodiments. Circuit layout 100 includes aplurality of routing tracks 102 for a metal level. Routing tracks 102 inFIG. 1A-1 are indicated as broken lines for clarity. Only one routingtrack 102 is labeled for clarity. Routing tracks 102 extend parallel toone another because the metal level uses a one-dimensional routingscheme. Circuit layout 100 includes a supply voltage (VDD) bus 104extending perpendicular to routing tracks 102. A reference voltage (VSS)bus 106 extends perpendicular to routing tracks 102 on an opposite sideof circuit layout 100 from VDD bus 104. The cell includes a plurality ofpins 112, 114 and 116 located between VDD bus 104 and VSS bus 106 andextending perpendicular to routing tracks 102. A first pin 112 has alength L1. A second pin 114 has a length L2. A third pin 116 has alength L3. VDD bus 104, VSS bus 106, pin 112, pin 114, and pin 116 arelocated on the same metal level. In some embodiments, VDD bus 104, VSSbus 106, pin 112, pin 114 and pin 116 are on a metal level closest to asubstrate, which is called a first metal level. Circuit layout 100further includes a global connection 120 extending across an entirety ofthe standard cell along a routing track 102. Global connection 120 islocated on a metal level farther from a substrate of the circuit layoutthan pins 112, 114, and 116. In some embodiments, a second metal levelfarther from the substrate than a first metal level is described asbeing “above” the first metal level. A first local connection 130extends parallel to global connection 120 and connects to first pin 112by a via. First local connection 130 is on a same metal level as globalconnection 120. A second local connection 140 extends parallel to globalconnection 120 and connects to second pin 114 by a via. Second localconnection 140 is on a same metal level as global connection 120 andfirst local connection 130. In some embodiments, global connection 120,local connection 130, and local connection 140 are located on the secondmetal level. Vias which provide connections between different metallevels are labeled with ‘X’ in circuit layout 100. Vias are able to belocated at access points. An access point is a location where a pin,e.g., pin 112, intersects with a routing track 102. These access pointsare located where local connections, e.g., first local connection 130 orsecond local connection 140, or global connections, e.g., globalconnection 120, extend above a pin. Second local connection 140 islocated on a same routing track 102 as first local connection 130. Anend-to-end separation S between first local connection 130 and secondlocal connection 140 is less than a minimum separation distance forcircuit layout 100. The cell also includes internal wiring 150, which islocated on a same metal level as VDD bus 104, VSS bus 106, pin 112, pin114 and pin 116, and is used to provide internal connections within thecell.

In some embodiments, the cell of circuit layout 100 is a standard cellretrieved from a cell library. Pins 112, 114 and 116 provide connectionpoints to transfer signals into and/or out of the cell. In someembodiments, global connection 120 is electrically connected to at leastone of pins 112, 114 or 116. In some embodiments, global connection 120is connected to every pin 112, 114 and 116. In some embodiments, globalconnection 120 is not connected to any of pins 112, 114 or 116. In someembodiments, global connection 120 is configured to carry a globalsignal such as a global clock signal, a supply voltage signal, areference voltage signal or another suitable global signal. A globalsignal is a signal which has substantially a same value usable bymultiple cells in a circuit layout. In some embodiments, the globalsignal is supplied to less than all cells in circuit layout 100.

First local connection 130 is configured to carry a local signal to pin112. A local signal is a signal having a specific value intended for aspecific cell and a specific pin or pins within the cell. In someembodiments, the local signal is an output from another cell, an inputfor another cell, a local clock signal or another suitable local signal.

Second local connection 140 is configured to carry a local signal to pin114. End-to-end separation S between first local connection 130 andsecond location connection 140 is less than the minimum separationdistance for circuit layout 100, which means that the first localconnection and the second location connection cannot be reliably formedin the location indicated in circuit layout 100. The minimum separationdistance is related to a process technology used to form circuit layout100. The minimum separation distance is based on patterning processes,formation processes and inherent manufacturing offset. In someembodiments, the minimum separation distance is a value set defined in atechnology file used by an automatic placement and routing (APR) tool.The APR tool performs design rule checking (DRC) in order to determinewhether the minimum separation distance and other design rules aresatisfied by elements within circuit layout 100. In the situation ofcircuit layout 100, the APR tool would indicate an error due to theend-to-end separation S between first local connection 130 and secondlocation connection 140.

In some embodiments, first local connection 130 and second localconnection 140 cannot be located in a routing track 102. If first localconnection 130 and second local connection 140 are in a routing track102, manufacturing circuit layout 100 has an increased risk of resultingin a faulty circuit.

FIG. 1B is an enlarged plan view of a cell in accordance with someembodiments. The cell includes elements from circuit layout 100 (FIG.1A-1). Same elements have a same reference number. A distance D betweenfirst pin 112 and second pin 114 is greater than the minimum separationdistance for the metal level. However, if distance D between adjacentpins 112 and 114 of the cell is small, first local connection 130 andsecond local connection 140 cannot be formed in a same routing track 102without violating the minimum separation distance design rule.

Returning to FIG. 1A-1, either first local connection 130 or secondlocal connection 140 should be moved to a different routing track 102 inorder to facilitate reliable manufacturing of circuit layout 100.However, moving either first local connection 130 or second localconnection 140 to another routing track 102 would include modificationof a standard cell layout. The modification of the standard cell layoutwould occur because pin 112 is connected to a local connection 130 whichis on the second metal level from one of the two access points, i.e.,the two locations where pin 112 and routing tracks 102 intersect, andpin 114 is connected to a local connection 140 which is on the secondmetal level from one of the two access points, i.e., the two locationswhere pin 114 and routing tracks 102 intersect. However, one accesspoint of pin 112 and one access point of pin 114 are blocked by globalconnection 120. In addition, local connections 130 and 140 cannot belocated on the same track due to spacing issues discussed above. As aresult, the layout of the standard cell is modified in order tofacilitate routing to the cell. Therefore, in order to resolve theend-to-end separation S error in circuit layout 100, a length of atleast one pin in circuit layout 100 is modified, in some embodiments.

FIG. 1A-2 is a plan view of the circuit layout 100′ including a modifiedcell in accordance with some embodiments. Circuit layout 100′ includesseveral elements which are the same as elements from circuit layout 100.Same elements have a same reference number. Elements of circuit layout100′ which are modified with respect to circuit layout 100 have a samereference number appended by a prime (′) symbol.

In comparison with circuit layout 100, circuit layout 100′ includesfirst pin 112′ having a length increased from L1 to L1′. A location oflocal connection 130′ is different from a location of local connection130 in circuit layout 100. The increased length of first pin 112′increases a number of access points for first pin 112′ to three, incomparison with two access points in circuit layout 100. By changing alocation of first local connection 130′, first local connection 130′ andsecond local connection 140 satisfy design rules. The increase in thedistance between first local connection 130′ and second local connection140 means that circuit layout 100′ is able to be reliably manufactured.In some embodiments, second local connection 140 is moved to a differentrouting track 102 and first local connection 130′ remains in a samerouting track 102 as in circuit layout 100. In some embodiments, lengthL1 of first pin 112 is maintained as a same length in circuit layout100′ as in circuit layout 100. In some embodiments, length L2 of secondpin 114 is adjusted in comparison with circuit layout 100.

Absent an ability to modify pins in circuit layout 100, which containsglobal connection 120, the cell would be unusable. In some embodiments,an unusable cell is called a dead cell. As a number of dead cells withina circuit layout increases, a utilization of the circuit layoutdecreases. The utilization of a circuit layout is based on a ratiobetween a total area of cells within a circuit layout and an overallarea of the circuit layout. Increasing utilization of a circuit layouthelps to facilitate overall size reduction of the circuit layout.

FIG. 2 is a plan view of a cell in a circuit layout 200 in accordancewith some embodiments. Circuit layout 200 includes similar elements ascircuit layout 100. Same elements have a same reference number increasedby 100. In comparison with circuit layout 100, circuit layout 200includes a fourth pin 218, and a fifth pin 220. FIG. 2 also includes anoverlap region 260 and a span region 270. Overlap region 260 is arouting track 202 where a greatest number of pins extend entirely acrossa routing track 202, e.g., pins 212, 214, 216, and 218. In someembodiments, overlap region 260 is called a maximum overlap region.Overlap region 260 is a candidate location for a global connection,e.g., global connection 120 (FIG. 1A-1). In some embodiments, pins 212,214, 216 and 218 which occupy overlap region 260 are called a maximumoverlapped pin group.

In order to help maintain usability of the cell in circuit layout 200, aspan width W from a left most pin location of the maximum overlapped pingroup to a right most pin location of the maximum overlapped pin groupshould be at least equal to a minimum span width. For example, in FIG.2, the span width W is a width of span region 270. Pin 220 is notconsidered for span width W of span region 270 because pin 220 is notincluded in overlap region 260. The minimum span width helps to ensurethat at least one global connection is able to be included in thecircuit layout as well as any local connections used by the circuitlayout. Increasing the minimum span width increases a number of routingsolutions for defining a usable cell. As a number of routing solutionsincreases, an amount of time for an APR tool to identify a suitablerouting scheme decreases. However, increasing the minimum span widthalso increases a size of the cell and the overall circuit layout. Theminimum span width is based in part on a number of pins in the maximumoverlapped pin group. As a number of pins in the maximum overlapped pingroup increases, the minimum span width also increases.

Circuit layout 200 includes four pins 212, 214, 216 and 218 in themaximum overlapped pin group. In some embodiments, the span width W forcircuit layout 200 is at least 278 nanometers (nm). In some embodimentswhere circuit layout includes three pins in the overlapped pin group,the span width W is at least 234 nm. In some embodiments where circuitlayout includes two pins in the overlapped pin group, the span width Wis at least 190 nm. In some embodiments where circuit layout includesone pin in the overlapped pin group, the span width W is at least 146nm. In some embodiments, the minimum span width differs from the abovevalues. The minimum span width is adjustable based on a pitch of routingtracks 202, dimensions of via cuts, an enclosure distance between a viacut and a metal wire, a number of pins in a maximum overlapped pingroup, a number of local connections, and other suitable variables.

A global connection tolerance K defines a maximum number of globalconnections that can be placed across a standard cell. The globalconnection tolerance K is determined based on a difference between anumber of routing tracks in a span region and a number of pins in amaximum overlapped pin group. The global connection tolerance K shouldbe either zero or a positive integer; otherwise, when K is less thanzero, the pins in the span region cannot be routed even when a globalconnection does not exist. The number of routing tracks in a span regionis determined based on a difference between an index of a rightmosttrack and an index of a leftmost track increased by one. For example,circuit layout 200 includes four pins in the maximum overlapped pingroup in overlap region 260. A number of routing tracks in the spanregion is five. As a result, a global connection tolerance K for circuitlayout 200 is one.

A global connection tolerance K greater than zero indicates that thecell layout is capable of receiving a global connection. As the globalconnection tolerance K increases, routing options for the cell layoutincrease which increases flexibility of the cell layout in variouscircuit designs.

FIG. 3 is a plan view of a cell in a circuit layout 300 in accordancewith some embodiments. Circuit layout 300 includes similar elements ascircuit layout 200. Same elements have a same reference number increasedby 100. In comparison with circuit layout 200, circuit layout 300includes pins oriented in a vertical direction in the plan view. Routingtracks 302 extend in a horizontal direction, perpendicular to pins 312,314, 316 and 318. Overlap region 360 also extends in the horizontaldirection. Circuit layout 300 includes a span width W′. Regardless of anorientation of pins, i.e., extending in a vertical direction or in thehorizontal direction, span width W′ is still at least equal to theminimum span width. That is, an orientation of pins in a circuit layoutdoes not impact the minimum span width. In some embodiments, circuitlayout 100 (FIG. 1A-1), circuit layout 100′ (FIG. 1A-2) or circuitlayout 200 (FIG. 2) is modified to have pins extending in the verticaldirection.

FIG. 4A is a plan view of a circuit layout 400 including a cell 410 anda blocking shape 420 in accordance with some embodiments. Circuit layout400 includes cell 410 which includes a plurality of pins 410 a-d. Pins410 a-d are located on a first metal layer and blocking shape 420 islocated on a second metal layer over cell 410. Blocking shape 420 isover an overlap region of pins 410 a, 410 c and 410 d. Due to thelocation of blocking shape 420, at least one routing track, e.g.,routing track 102 (FIG. 1), is unavailable for global or localconnections to pins 410 a, 410 c, and 410 d. To increase a number ofrouting solutions for cell 410, an APR tool is usable to adjust alocation of cell 410 within circuit layout 400. For example, the APRtool adjusts the location of cell 410 in a direction perpendicular toblocking shape 420, in some embodiments.

In some embodiments, blocking shape 420 is a type of a globalconnection. In some embodiments, blocking shape 420 is a power-groundline. In some embodiments, blocking shape 420 is another interconnectstructure within circuit layout 400. In some embodiments, a location ofblocking shape 420 prevents routing of a global or a local connection tocell 410. To increase a number of routing solutions for circuit layout400, lengths of pins 410 a-d are adjusted in some embodiments. In someembodiments, a location of cell 410 is adjusted within circuit layout400 in order to reduce the impact of blocking shape 420 or avoid theblocking shape entirely.

FIG. 4B is a plan view of a circuit layout 400′ including a cell 410 anda blocking shape 420 in accordance with some embodiments. In comparisonwith circuit layout 400, circuit layout 400′ includes cell 410′ which isa neighboring cell adjacent to cell 410. Routing local connections orglobal connections in cell 410′ impacts routing solutions for cell 410due to the proximity between cell 410 and cell 410′, in some instances.For example, there are not sufficient routing resources on a third metallevel, in some instances.

FIG. 4C is a plan view of a circuit layout 400″ including a cell 410 anda blocking shape 420 in accordance with some embodiments. In comparisonwith circuit layout 400′, circuit layout 400″ includes cell 410′ locatedat a position away from cell 410. Increasing a distance between cell 410and cell 410′ increases the number of routing solutions for circuitlayout 400″ in comparison with circuit layout 400′. For example,increasing the distance provides more routing resources for the firstmetal level and the third metal level.

FIG. 5A is a flow chart of a method of modifying a cell based on globalconnection tolerance in accordance with some embodiments. In operation502, a number of routing tracks in a span region and a number of pins ina maximum overlapped pin group of a cell are identified. In someembodiments, the number of pins in the maximum overlapped pin group isdetermined by using a design tool. In some embodiments, the number ofpins in the maximum overlapped pin group is received from a user.

In operation 504, a global connection tolerance K of the cell isdetermined. The global connection tolerance K is determined based on anumber of pins in a maximum overlapped pin group of the cell and on anumber of routing tracks within a span region of the cell. The number ofrouting tracks in the span region is determined based on a differencebetween an index of a rightmost track and an index of a leftmost trackincreased by one. FIGS. 2 and 3 above provide examples of how a numberof pins in a maximum overlapped pin group is determined as well as how anumber of routing tracks in a span region is determined, in someembodiments.

In comparison 506, the global connection tolerance K is compared with athreshold value. The threshold value is a desired global connectiontolerance. In some embodiments, the threshold value is retrieved from alook-up table. In some embodiments, the threshold value is calculatedbased on the parameters of an integrated circuit. In some embodiments,the threshold value is provided by a user.

If the comparison 506 determines that the global connection tolerance Ksatisfies the threshold value, method 500 continues to operation 508 inwhich the cell is stored in a cell library. In some embodiments, thecell is associated with a global connection tolerance value. In someembodiments, the cell is stored without being associated with a globalconnection tolerance value. In some embodiments, the cell library isusable by a circuit designer for designing a circuit layout.

If the comparison 506 determines that the global connection tolerance Kfails to satisfy the threshold value, method 500 continues withoperation 510 in which a length of at least one pin of the cell isadjusted or a position of at least one pin in the cell is adjusted. Insome embodiments, operation 510 includes only adjusting the length of atleast one pin of the cell. In some embodiments, operation 510 includesonly adjusting the position of at least one pin of the cell. In someembodiments, operation 510 includes both adjusting the length of atleast one pin of the cell and adjusting the position of at least one pinof the cell. In some embodiments, a length of a first pin is adjusted inoperation 510 and a position of a second pin, different from the firstpin, is adjusted in operation 510. In some embodiments, a length and aposition of a same pin are adjusted in operation 510.

The length of at least one pin of the cell is adjusted as describedabove with respect to FIGS. 1A-1 and 1A-2. In some embodiments, a lengthof every pin in the cell is adjusted. In some embodiments, a length ofless than every pin in the cell is adjusted. Adjusting the length of atleast one pin in the cell increases locations for connection to the pinhaving the adjusted length. As a result, a global connection toleranceof the cell is changed, in some instances. Following operation 510,method 500 returns to operation 502 to determine a number of routingtracks in a span region and a number of pins in a maximum overlapped pingroup of the modified cell.

FIG. 5B is a flow chart of a method 500′ of designing a circuit layoutbased on global connection routing in accordance with some embodiments.In operation 512, a global connection tolerance (K) of a cell isdetermined. The global connection tolerance K should be either zero or apositive integer number. The global connection tolerance K of a cell isthe ability of a cell to tolerate global connections. A globalconnection tolerance K greater than zero indicates that the cell is nota dead cell, i.e., the cell is capable of allowing at least one globalconnection extending across the cell. A high global connection toleranceK indicates that the cell has a large number of possible routingsolutions for accessing pins within a cell when only one globalconnection passes the cell, which increases the likelihood of a routingsolution for the cell which renders the cell usable. In someembodiments, the global connection tolerance K is determined based on avalue stored in a cell library associated with the cell. In someembodiments, the global connection tolerance K is determined byidentifying a span region for a maximum overlapped pin group;identifying a routing track closest to a first edge of the cell usableto connect to a pin of the cell; identifying a routing track closest toa second edge of the cell, opposite the first edge of the cell, usableto connect to a pin of the cell; and identifying a number of pins in thecell. In some embodiments where the cell includes pins extendinghorizontally, the global connection tolerance K is determined byidentifying a left most routing track usable to connect to a pin of thecell; identifying a right most routing track usable to connect to a pinof the cell; and identifying a number of pins in the cell. In someembodiments where the cell includes pins extending vertically, theglobal connection tolerance K is determined by identifying a top mostrouting track usable to connect to a pin of the cell; identifying abottom most routing track usable to connect to a pin of the cell; andidentifying a number of pins in the cell.

An example of how a global connection tolerance K is calculated isprovided based on an example cell in FIG. 6. FIG. 6 is a plan view of acell 600 including pins 612-616 in accordance with some embodiments.FIG. 6 includes cell 600 with a plurality of routing tracks 602 for ahigher metal level superimposed over the cell. Each of the routingtracks includes an index, the index begins at zero for a routing trackon an edge of cell 600 in the given embodiment. A span region 620 ofcell 600 indicates a span of a maximum overlapped pin group, i.e., pins612, 614 and 616. In the example of cell 600 an index of a right mostrouting track usable to connect to a pin in the span region of cell 600is “7.” Pin 614 extends entirely through a routing track 602 having theindex of “7.” A left most routing track usable to connect to a pin inthe span region of cell 600 is “2.” While pin 616 extends into routingtrack 602 having the index of “1,” pin 616 extends across less than theentirety of the index “1” routing track. Therefore, connecting to pin616 in routing track “1” will present issues with decreasedmanufacturing reliability. As a result, the left most routing trackusable for connecting to pin 616 is routing track “2.” A number of pinsin a maximum overlapped pin group of cell 600 is 3, pins 612-616. Basedon the information given above, a global connection tolerance of cell600 is 3.

While cell 600 includes pins extending horizontally, methods 500 and500′ are also applicable to cells having pins extending vertically.

In operation 514 of method 500′, a number of blocked tracks B of thecell is determined. Similar to FIGS. 4A-4C, blocking shapes located on ametal level above pins of the cell prevent connection to the pins. Thenumber of blocked tracks B is determined based on a pin blocking shapegroup.

An example of how a number of blocked tracks B is calculated is providedbased on an example cell in FIG. 7. FIG. 7 is a plan view of a cell 700including pins 712-716 and blocking shapes 772 and 774 in accordancewith some embodiments. Cell 700 is similar to cell 600. Same elementshave a same reference number increased by 100. In comparison with cell600, cell 700 includes a pin blocking shape group 770 that blocks anumber of routing tracks 702. Pin blocking shape group 770 includes afirst blocking shape 772 and a second blocking shape 774. Blockingshapes 772 and 774 are located on a metal level above pins of the cell.In some embodiments, first blocking shape 772 or second blocking shape774 is independently selected from power-ground lines or otherinterconnect structures.

Pin blocking shape group 770 extends across four routing tracks, routingtracks “4,” “5,” “6,” and “7.” Therefore, a number of blocked tracks incell 700 is four. In some embodiments, pin blocking shape group 770includes a single blocking shape. In some embodiments, pin blockingshape group 770 includes more than two blocking shapes.

Returning to FIG. 5B, method 500′ continues with comparison 516. Incomparison 516, the global connection tolerance K of the cell iscompared with the number of blocked tracks B of the cell. If the globalconnection tolerance K is less than the number of blocked tracks B, thecell will be unusable, i.e., a dead cell. The cell will be unusablebecause there will be no routing scheme solution for the cell due to thelarge number of blocked routing tracks of the cell relative to the smallnumber of connection points for the cell.

If the global connection tolerance K of the cell is less than the numberof blocked tracks B of the cell (meaning a predetermined condition isnot satisfied), then method 500′ continues to operation 518 in order tomodify a location of the cell in the circuit layout. In someembodiments, the predetermined condition is the global connectiontolerance K being less than the number of blocked tracks B. In someembodiments, one or more additional buffers which are close to the cellare inserted into the circuit layout in order to adjust a location ofthe cell. However, providing one or more desired buffers will alsoincrease a size of the overall circuit layout, in some instances. Also,the use of desired buffers will increase a number of feedbacks fromcomparison 516 to operation 518, in some instances.

The location of the cell is adjusted as described above with respect toFIGS. 4A-4C. In some embodiments, the location of the cell is adjustedto change a location of a blocking shape relative to the cell. In someembodiments, the location of the cell is adjusted to locate the cellcompletely separate from the blocking shape.

Following operation 518, method 500′ returns to operation 514 todetermine a number of blocked tracks B for the modified cell location.

If the global connection tolerance K and the number of blocked tracks Bsatisfy the predetermined condition, then method 500′ continues tooptional operation 520. In some embodiments, if the global connectiontolerance K is equal to or greater than the number of blocked tracks B,then method 500′ continues to optional operation 520. In optionaloperation 520, instructions for forming a mask based on the circuitlayout are generated. In some embodiments, operation 520 is omitted ifthere are other cells which need to be checked for the predeterminedcondition. In some embodiments, operation 520 is omitted if the mask isto be formed by a different entity from the one generating the circuitlayout. A mask is used in a lithography process in order to pattern awafer to form the device in the substrate. In some embodiments, theinstructions for forming the mask are generated using a same tool asthat used to analyze and modify the circuit layout. In some embodiments,the instructions for forming the mask are generated by using a differenttool from that used to analyze and modify the circuit layout. In someembodiments, additional operations are performed prior to generating theinstructions for forming the mask. In some embodiments, the additionaloperations include a layout-versus-schematic (LVS) check, a design rulescheck (DRC), a simulation of the resistance-capacitance (RC) performanceof the circuit layout, or other suitable operations.

In some embodiments, additional operations are included in method 500′,such as LVS check, DRC, RC simulation, or other suitable operations. Insome embodiments, an order of operations for method 500′ is modified. Insome embodiments, multiple operations for method 500′ are performedsimultaneously. For example, in some embodiments, operation 514 andoperation 518 are performed simultaneously. In some embodiments,operations from method 500 (FIG. 5A) are combined with operations frommethod 500′. For example, in some embodiments, method 500′ alters alength of a pin or a location of a pin within a cell to adjust a globalconnection tolerance K similar to operation 510 in method 500.

FIG. 8 is a schematic diagram of a specific purpose system forimplementing a method of global connection routing in accordance withsome embodiments. System 800 includes a hardware processor 802 and anon-transitory, computer readable storage medium 804 encoded with, i.e.,storing, the computer program data 806, i.e., a set of programvariables. Computer readable storage medium 804 is also encoded withinstructions 807 for interfacing with other machines and forimplementing a method of global connection routing, e.g., method 500 ormethod 500′ (FIGS. 5A and 5B). The processor 802 is electrically coupledto the computer readable storage medium 804 via a bus 808. The processor802 is also electrically coupled to an I/O interface 810 by bus 808. Anetwork interface 812 is also electrically connected to the processor802 via bus 808. Network interface 812 is connected to a network 814, sothat processor 802 and computer readable storage medium 804 are capableof connecting to external elements via network 814. The processor 802 isconfigured to execute the computer program code 806 or 807 encoded inthe computer readable storage medium 804 in order to cause system 800 tobe usable for performing a portion or all of the operations as describedin method 500 or method 500′ (FIGS. 5A and 5B). During execution ofmethod 500 or method 500′, additional information is stored in or readfrom memory 804, in some embodiments.

In some embodiments, the processor 802 is a central processing unit(CPU), a multi-processor, a distributed processing system, anapplication specific integrated circuit (ASIC), and/or a suitableprocessing unit.

In some embodiments, the computer readable storage medium 804 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example, the computerreadable storage medium 804 includes a semiconductor or solid-statememory, a magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk, and/or anoptical disk. In some embodiments, the computer readable storage medium804 includes an optical disk, such as a compact disk-read only memory(CD-ROM), a compact disk-read/write (CD-R/W), and/or a digital videodisc (DVD).

In some embodiments, the storage medium 804 stores the computer programcode 806 or 807 configured to cause system 800 to perform method 500 ormethod 500′ (FIGS. 5A and 5B). In some embodiments, the storage medium804 also stores information needed for performing a method 500 or method500′ (FIGS. 5A and 5B) as well as information generated duringperforming the method 500 or method 500′, such as a pin length parameter816, a global connection tolerance parameter 818, a blocked tracksparameter 820, a cell location parameter 822, and/or a set of executableinstructions to perform the operation of method 500 or method 500′(FIGS. 5A and 5B).

In some embodiments, the storage medium 804 stores instructions 807 forinterfacing with manufacturing machines. The instructions 807 enableprocessor 802 to generate manufacturing instructions readable by themanufacturing machines to effectively implement method 500 or method500′ (FIGS. 5A and 5B) during a global connection routing process.During execution of method 500 or method 500′, additional information isstored in or read from memory 804, in some embodiments.

System 800 includes I/O interface 810. I/O interface 810 is coupled toexternal circuitry. In some embodiments, I/O interface 810 includes akeyboard, keypad, mouse, trackball, trackpad, and/or cursor directionkeys for communicating information and commands to processor 802.

System 800 also includes network interface 812 coupled to the processor802. Network interface 812 allows system 800 to communicate with network814, to which one or more other computer systems are connected. Networkinterface 812 includes wireless network interfaces such as BLUETOOTH,WIFI, WIMAX, GPRS, or WCDMA; or wired network interface such asETHERNET, USB, or IEEE-1394. In some embodiments, method 500 or method500′ is implemented in two or more systems 800, and information such aspin length, global connection tolerance, blocked tracks and celllocation are exchanged between different systems 800 via network 814.

System 800 is configured to receive information related to a pin lengthof pins in a cell through I/O interface 810 or network interface 812.The information is transferred to processor 802 via bus 808 to place thecell in a circuit layout. The pin length is then stored in computerreadable medium 804 as pin length parameter 816. System 800 isconfigured to determine information related to global connectiontolerance during execution of method 500 or method 500′ (FIGS. 5A and5B). In some embodiments, system 800 is configured to receiveinformation related to global connection tolerance through I/O interface810 or network interface 812. The information is stored in computerreadable medium 804 as global connection tolerance parameter 818. System800 is configured to determine information related to blocked tracksduring execution of method 500 or method 500′ (FIGS. 5A and 5B). In someembodiments, system 800 is configured to receive information related toblocked tracks through I/O interface 810 or network interface 812. Theinformation is stored in computer readable medium 804 as blocked tracksparameter 820. System 800 is configured to receive information relatedto cell location through I/O interface 810 or network interface 812. Insome embodiments, system is configured to determine information relatedto cell location during execution of method 500 or method 500′ (FIGS. 5Aand 5B). The information is stored in computer readable medium 804 ascell location parameter 822.

System 800 is a specific purpose computing device which is configuredfor executing method 500 or method 500′ (FIGS. 5A and 5B). While system800 may include components which are usable in other computing devices,system 800 is configured for the specific purpose of executing a methodof global connection routing.

One aspect of this description relates to a method of modifying a cell.The method includes identifying a maximum overlapped pin group. Themethod further includes determining a number of pins in the maximumoverlapped pin group. The method further includes determining a spanregion of the maximum overlapped pin group. The method further includescomparing the number of pins and the span region to determine a globaltolerance of the cell. The method further includes increasing a lengthof at least one pin of the maximum overlapped pin group in response tothe global tolerance failing to satisfy a predetermined threshold. Themethod further includes fabricating a mask based on the increased lengthof the at least one pin. In some embodiments, the determining of thespan region includes subtracting a first routing track number covered bya first pin in the maximum overlapped pin group from a second routingtrack number covered by a second pin of the maximum overlapped pingroup, the first pin is the pin of the maximum overlapped pin groupclosest to a first edge of the cell, the second pin is the pin of themaximum overlapped pin group closest to a second edge of the cell, andthe first edge of the cell is opposite the second edge of the cell. Insome embodiments, the first pin is different from the second pin. Insome embodiments, the identifying of the maximum overlapped pin groupincludes determining a routing track of the cell overlapped by agreatest number of pins; and identifying each pin overlapping therouting track as part of the maximum overlapped pin group. In someembodiments, the method further includes storing the cell including theat least one pin having the increased length in a cell library. In someembodiments, the method further includes retrieving the predeterminedthreshold from a look-up table, wherein the increasing the length of theat least one pin includes increasing the length of the at least one pinin response to the global tolerance failing to satisfy the retrievedvalue. In some embodiments, the method further includes receiving thepredetermined threshold from a user, wherein the increasing the lengthof the at least one pin includes increasing the length of the at leastone pin in response to the global tolerance failing to satisfy thereceived value. In some embodiments, the method further includesadjusting a position of the at least one pin in response to the globaltolerance failing to satisfy the predetermined condition. In someembodiments, the method further includes adjusting a position of asecond pin of the maximum overlapped pin group in response to the globaltolerance failing to satisfy the predetermined condition, wherein thesecond pin is different from the at least one pin. In some embodiments,the method further includes determining a number of blocked tracks ofthe cell, wherein determining whether the global tolerance satisfies thepredetermined condition is based on the number of blocked tracks.

Another aspect of this description relates to a method of globalconnection routing. The method includes identifying a maximum overlappedpin group for a cell. The method further includes determining a numberof pins in the maximum overlapped pin group. The method further includesdetermining a span region of the maximum overlapped pin group. Themethod further includes comparing the number of pins and the span regionto determine a global tolerance of the cell. The method further includesdetermining a number of blocked tracks of the cell. The method furtherincludes shifting a location of an entirety of the cell in response tothe number of blocked tracks being greater than the global tolerance.The method further includes fabricating a mask based on the shiftedlocation of the cell. In some embodiments, the method further includesshifting the location of the entirety of the cell in response to thenumber of blocked tracks being equal to the global tolerance. In someembodiments, the determining of the number of blocked tracks includesdetermining a number of routing tracks of the cell overlapped bypower/ground lines in a layer above the cell. In some embodiments, theshifting of the location of the entirety of the cell includespositioning the cell to reduce the number of blocked tracks. In someembodiments, the shifting of the location of the entirety of the cellincludes positioning the cell to avoid all blocked tracks.

Still another aspect of this description relates to a method ofmodifying a cell. The method includes identifying a maximum overlappedpin group. The method further includes determining a number of pins inthe maximum overlapped pin group. The method further includesdetermining a span region of the maximum overlapped pin group. Themethod further includes comparing the number of pins and the span regionto determine a global tolerance of the cell. The method further includesadjusting a location of an end of at least one pin of the maximumoverlapped pin group in response to the global tolerance failing tosatisfy a predetermined threshold. The method further includesfabricating a mask based on the adjusted location of the end of the atleast one pin. In some embodiments, the adjusting the location of theend of the at least one pin includes shifting a position of an entiretyof the cell. In some embodiments, the adjusting the location of the endof the at least one pin includes increasing a length of the at least onepin within the cell. In some embodiments, the adjusting the location ofthe end of the at least one pin includes shifting a position of the atleast one pin within the cell. In some embodiments, the method furtherincludes iteratively determining the global tolerance of the cell andthe adjusting of the location of the end of the at least one pin inresponse to the global tolerance failing to satisfy the predeterminedthreshold until the global tolerance satisfies the predeterminedthreshold.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of modifying a cell, the methodcomprising: identifying a maximum overlapped pin group region;determining a number of pins in the maximum overlapped pin group region;determining a number of routing tracks within a span region of themaximum overlapped pin group region; comparing the number of pins andthe number of routing tracks within the span region to determine aglobal tolerance of the cell; increasing a length of at least one pin ofthe maximum overlapped pin group in response to the global tolerancefailing to satisfy a predetermined threshold; and fabricating a maskbased on the increased length of the at least one pin.
 2. The method ofclaim 1, wherein the determining of the span region comprisessubtracting a first routing track number covered by a first pin in themaximum overlapped pin group region from a second routing track numbercovered by a second pin of the maximum overlapped pin group region, thefirst pin is the pin of the maximum overlapped pin group region closestto a first edge of the cell, the second pin is the pin of the maximumoverlapped pin group region closest to a second edge of the cell, andthe first edge of the cell is opposite the second edge of the cell. 3.The method of claim 2, wherein the first pin is different from thesecond pin.
 4. The method of claim 1, wherein the identifying of themaximum overlapped pin group region comprises: determining the number ofrouting tracks of the cell overlapped by a greatest number of pins; andidentifying each pin overlapping one of the routing tracks as part ofthe maximum overlapped pin group region.
 5. The method of claim 1,further comprising storing the cell including the at least one pinhaving the increased length in a cell library.
 6. The method of claim 1,further comprising retrieving the predetermined threshold from a look-uptable, wherein the increasing the length of the at least one pincomprises increasing the length of the at least one pin in response tothe global tolerance failing to satisfy the retrieved value.
 7. Themethod of claim 1, further comprising receiving the predeterminedthreshold from a user, wherein the increasing the length of the at leastone pin comprises increasing the length of the at least one pin inresponse to the global tolerance failing to satisfy the received value.8. The method of claim 1, further comprising adjusting a position of theat least one pin in response to the global tolerance failing to satisfythe predetermined condition.
 9. The method of claim 1, furthercomprising adjusting a position of another pin of the maximum overlappedpin group region in response to the global tolerance failing to satisfythe predetermined condition, wherein the second pin is different fromthe at least one pin.
 10. The method of claim 1, further comprisingdetermining a number of blocked tracks of the cell, wherein determiningwhether the global tolerance satisfies the predetermined condition isbased on the number of blocked tracks.
 11. A method of global connectionrouting, the method comprising: identifying a maximum overlapped pingroup region for a cell; determining a number of pins in the maximumoverlapped pin group region; determining a number of routing trackswithin a span region of the maximum overlapped pin group region;comparing the number of pins and the number of routing tracks within thespan region to determine a global tolerance of the cell; determining anumber of blocked tracks of the cell; shifting a location of an entiretyof the cell in response to the number of blocked tracks being greaterthan the global tolerance; and fabricating a mask based on the shiftedlocation of the cell.
 12. The method of claim 11, further comprisingshifting the location of the entirety of the cell in response to thenumber of blocked tracks being equal to the global tolerance.
 13. Themethod of claim 11, wherein the determining of the number of blockedtracks comprises determining the number of routing tracks of the celloverlapped by power/ground lines in a layer above the cell.
 14. Themethod of claim 11, wherein the shifting of the location of the entiretyof the cell comprises positioning the cell to reduce the number ofblocked tracks.
 15. The method of claim 11, wherein the shifting of thelocation of the entirety of the cell comprises positioning the cell toavoid all blocked tracks.
 16. A method of modifying a cell, the methodcomprising: identifying a maximum overlapped pin group region;determining a number of pins in the maximum overlapped pin group region;determining a number of routing tracks within a span region of themaximum overlapped pin group region; comparing the number of pins andthe number of routing tracks within the span region to determine aglobal tolerance of the cell; adjusting a location of an end of at leastone pin of the maximum overlapped pin group region in response to theglobal tolerance failing to satisfy a predetermined threshold; andfabricating a mask based on the adjusted location of the end of the atleast one pin.
 17. The method of claim 16, wherein the adjusting thelocation of the end of the at least one pin comprises shifting aposition of an entirety of the cell.
 18. The method of claim 16, whereinthe adjusting the location of the end of the at least one pin comprisesincreasing a length of the at least one pin within the cell.
 19. Themethod of claim 16, wherein the adjusting the location of the end of theat least one pin comprises shifting a position of the at least one pinwithin the cell.
 20. The method of claim 16, further comprisesiteratively determining the global tolerance of the cell and theadjusting of the location of the end of the at least one pin in responseto the global tolerance failing to satisfy the predetermined thresholduntil the global tolerance satisfies the predetermined threshold.